The present invention relates to a polycarbonate resin composition. More precisely, the invention relates to a polycarbonate resin composition having good durability even in high-humidity atmosphere, and to a flame-retardant polycarbonate resin composition in which the flame retardant adheres little to molds.
As having the advantages of impact resistance, heat resistance and good electric properties, polycarbonate resins have many applications in various fields of, for example, OA (office automation) appliances, information and communication appliances, other electric and electronic appliances for industrial use and household use, automobile parts and building materials. Polycarbonate resins are self-extinguishable. However, some fields of typically OA appliances, information and communication appliances, and other electric and electronic appliances for industrial use and household use require higher flame retardancy, for which are used various flame retardants to improve their flame retardancy.
For improving the flame retardancy of polycarbonate resins, halogen-containing flame retardants such as bisphenol A halides and halogenated polycarbonate oligomers have been used along with a flame retardation promoter such as antimony oxide, as their flame-retarding ability is good. However, with the recent tendency toward safety living and environmental protection from discarded and incinerated wastes, the market requires flame retardation with non-halogen flame retardants. As non-halogen flame retardants, phosphorus-containing organic flame retardants, especially organic phosphate compounds may be added to polycarbonate resin compositions, for which various methods have been proposed. Such flame retardants, organic phosphate compounds serve also as a plasticizer, and polycarbonate resin compositions containing them exhibit excellent flame retardancy.
It is known to stabilize polycarbonate resins with organic phosphorus compounds added thereto, for example, as in Japanese Patent Publication No. 22088/1972 and Japanese Patent Laid-Open No. 90254/1985. However, in order to make polycarbonate resins resistant to flames by adding thereto a phosphate compound, a relatively large amount of the compound must be added to the resins. Polycarbonate resins require relatively high molding temperatures, and their melt viscosity is high. Therefore, for molding them into thin-walled and large-sized moldings, the molding temperature will have to be more and more higher. For these reasons, phosphate compounds often cause some problems when added to such polycarbonate resins, though their flame-retarding ability is good. For example, phosphate compounds often adhere to molds used for molding resins containing them, and, when the moldings containing them are left in high-temperature and high-humidity atmospheres, the compounds lower the impact strength of the moldings and yellow the moldings.
In Japanese Patent Laid-Open No. 283760/1990, proposed is a method of adding a hydroxyl group-having phosphorus compound such as phosphorous acid or phosphoric acid to a polycarbonate resin composition containing an inorganic filler, for stabilizing the filler in the composition. In this case, the phosphorus compound added to the resin composition is effective for stabilizing the inorganic filler in the composition. However, this is problematic in that, when the moldings of the resin composition are used in high-humidity atmospheres, their durability is lowered as the molecular weight of the polycarbonate resin therein is lowered, and, in addition, it is often difficult to recycle the moldings.
In Japanese Patent Laid-Open Nos. 228764/1995 and 239565/1996, proposed is a polycarbonate resin composition comprising a polycarbonate resin and a styrenic resin and containing a phosphate compound and talc.
When polycarbonate resins containing an inorganic filler such as talc are molded at high temperatures or when their moldings are recycled, the molecular weight of the resins is lowered to cause some problems in that the physical properties of the resin moldings are worsened and the moldings are much yellowed.
The present invention is to provide a polycarbonate resin composition having good durability even in high-humidity atmospheres and to provide a flame-retardant polycarbonate resin composition in which the flame retardant adheres little to molds.
We, the present inventors have assiduously studied in order to solve the problems in the prior art, and, as a result, have found that, when a suitable amount of an arylphosphine is added to a resin composition comprising a polycarbonate resin and an inorganic filler, then the above-mentioned object can be attained. On the basis of this finding, we have completed the present invention.
Specifically, the invention is summarized as follows:
[1] A polycarbonate resin composition comprising (A) from 50 to 99.9% by weight of a polycarbonate resin and (B) from 0.1 to 50% by weight of an inorganic filler, and containing (C) from 0.01 to 1 part by weight, relative to 100 parts by weight of the total of (A) and (B), of an arylphosphine of a general formula [1]:
Pxe2x88x92(X)3 xe2x80x83xe2x80x83[1]
wherein X represents a hydrocarbon group, and at least one X is an optionally-substituted aryl group having from 6 to 18 carbon atoms.
[2] The polycarbonate resin composition of above [1], wherein the inorganic filler (B) is talc or mica.
[3] The polycarbonate resin composition of above [1] or [2], wherein the inorganic filler (B) is talc having a mean particle size of from 0.2 to 20 xcexcm.
[4] The polycarbonate resin composition of any of above [1] to [3], wherein the arylphosphine (C) is triphenylphosphine.
[5] The polycarbonate resin composition of any of above [1] to [4], which further contains (D) from 0.1 to 20 parts by weight, relative to 100 parts by weight of the total of the polycarbonate resin (A) and the inorganic filler (B), of a flame retardant.
[6] The polycarbonate resin composition of above [5], wherein the flame retardant (D) is one or more selected from the group of phosphates, red phosphorus and silicone compounds.
[7] The polycarbonate resin composition of above [5] or [6], which further contains (E) from 1 to 40 parts by weight, relative to 100 parts by weight of the total of the polycarbonate resin (A) and the inorganic filler (B), of a styrenic resin.
[8] The polycarbonate resin composition of above [7], wherein the styrenic resin (E) is a rubber-modified styrenic resin.
[9] The polycarbonate resin composition of any of above [5] to [8], which further contains (F) from 0.01 to 5 parts by weight, relative to 100 parts by weight of the total of the polycarbonate resin (A) and the inorganic filler (B), of a polyfluoro-olefin resin.
[10] The polycarbonate resin composition of above [9], wherein the polyfluoro-olefin resin (F) is a polytetrafluoroethylene having the ability to form fibrils and having a mean molecular weight of at least 500,000.
[11] Housings or parts of electric and electronic appliances, made by molding the polycarbonate resin composition of any of above [1] to [10].